BEMBEN, D. A., N. L. FETTERS, M. G. BEMBEN, N. NABAVI, and E. T. KOH. Musculoskeletal responses to high- and low-intensity resistance training in early postmenopausal women. Med. Sci. Sports Exerc., Vol. 32, No. 11, pp. 1949–1957, 2000. The purpose of this study was to compare the effects of a high-load (80%, 1-repetition maximum (RM), 8 reps) and a high-repetition (40%, 1-RM, 16 reps) resistance training protocol on muscular strength and bone mineral density (BMD) in early postmenopausal, estrogen-deficient women. The 6-month programs were matched initially for training volume (3 sets, 3 d·wk−1) for 12 exercises selected to specifically load the spine and hip. Subjects included 25 women (41–60 yr) who were matched by spine BMD then randomly assigned to either the high-load (HL, N = 10), high-repetition (HR, N = 7), or control (C, N = 8) groups. Dietary calcium intakes were supplemented to ∼1500 mg·d−1. Total body, spine, and hip BMD (DXA, Lunar Model DPX-IQ), upper and lower body muscular strength, and biochemical markers of bone turnover were measured at baseline and after 6 months of training. There were no group differences in the baseline measures. Both training groups showed similar increases in biceps (20%) and rectus femoris (28–33%) cross-sectional areas, in lower body strength (∼30%) and in hip strength (37–40%). HL showed greater improvements in upper body strength (HL 25%, HR 16%). Neither training group experienced significant increases in spine or hip BMD, although the HL total body BMD tended to decrease (−1.1% ± 0.4, P = 0.054) after training. Osteocalcin tended to increase (P = 0.08) in all groups after training, and the % change in osteocalcin was positively related to % changes in the total hip (r = 0.41, P = 0.048) and the trochanter (r = 0.42, P = 0.04) BMD. The high-load and high-repetition resistance training protocols were both effective in improving muscular strength and size in postmenopausal women, indicating low-intensity resistance training can be beneficial for the muscular fitness in women for whom high-intensity exercise is contraindicated.

Prolonged unloading of bone(s) in the residual limb after amputation may cause significant bone loss in the hip and distal bony end of the residual limb. The purpose of this study was to examine the effect of amputation on bone geometry, volumetric BMD (vBMD), and areal BMD (aBMD) by comparing the intact and residual limbs in unilateral transfemoral and transtibial amputees. Amputees (seven above-knee; seven below-knee) and two groups of nonamputee control subjects gave informed consent to participate in this study. aBMD of the dual proximal femur, lumbar spine, and total body was assessed using DXA. Bone geometry and vBMD were assessed at the distal ends of the residual limb and intact limb and at a comparable cross-sectional slice of the intact limb using pQCT (Stratec XCT 3000). There were no significant group differences in age, height, weight, physical activity, time as an amputee, hours wearing a prosthesis per day, or total body and lumbar spine BMD and BMC. There were significant side × group interactions for total hip, femoral neck, and trochanter BMD, with the amputated side having lower BMD, and differences being most severe in above-knee amputees. Total and cortical vBMD and area were significantly lower at the end of the residual limb compared with the similar slice of the intact limb for both above- and below-knee amputees. In conclusion, amputees exhibited large decrements in BMD, both at the hip and at the end of the residual limb, compared with the intact side. These lower BMD values put amputees, particularly the above-knee amputees, at increased risk for osteoporosis and fragility fractures in the hip.

Th, and sarcopenia status. The purpose of this study was to examine jump performance, muscle strength, and sarcopenia status in older adults. Methods: This was a cross-sectional study that included men (n = 27) and women (n = 33) (55–75 years) recruited from the general community. Participants completed health status and physical activity questionnaires. Body composition, including appendicular skeletal muscle mass (ASM), bone free lean body mass, and relative skeletal muscle mass index, were assessed by total body dual-energy x-ray absorptiometry scans. The criteria for sarcopenia were relative skeletal muscle mass index values less than 7.26 kg/m2 for men and less than 5.45 kg/m2 for women. Three vertical jumps on a jump mat were performed to assess JPow, jump velocity (JVel), and jump height (JHt). Muscle strength was measured by 1RM testing for leg press (LP) and right and left hip abduction isotonic resistance exercises. Results: Sarcopenia was found in 20% (12/60) of the participants. Jump power was significantly lower (P = .001) in the sarcopenia group than in the normal group, 651.1 (41.7) W versus 851.0 (27.4) W, respectively. Jump power and JHt were significantly (P < .01) positively correlated (r = 0.54−0.77) with ASM and bone free lean body mass. Significant (P < .01) positive correlations (r = 0.43−0.70) were also reported between jump test variables (JPow, JVel, JHt) and muscle strength (LP, right and left hip abduction). Discussion: The jump test protocol was conducted safely with no injuries or balance issues. Our finding of lower JPow in sarcopenic individuals adds new information to the existing literature on age-related declines in muscle power. Conclusion: Community-dwelling individuals classified as sarcopenic had significantly lower JPow but not muscle strength compared with their counterparts with normal amounts of muscle mass. Jump test variables were positively correlated with lean tissue and lower body muscle strength. Based on our findings, JPow may be useful for sarcopenia screening in the middle-aged and older adults; however, more research is needed to determine the utility of this method in clinical populations....

Body mass-matched controls (n = 30). Methods: The cyclists had an average of 9.4 yr of racing experience and trained 7-22 h·wk−1. BMD was measured using dual energy x-ray absorptiometry (DXA; GE Lunar Prodigy, v. 6.70.021). Calcium intake was estimated from a food frequency questionnaire. Resting serum total and free testosterone levels were measured by RIA (Diagnostic Systems Laboratory). Results: There were no significant differences (P > 0.050) between the cyclists (CYC) and the controls (CON) for age, height, body mass, or testosterone levels. CYC had significantly (P < 0.050) lower percent body fat and higher bone-free lean body mass than the CON. Calcium intake for CYC was significantly higher (P < 0.050) than for the CON group (1557 ± 132 vs 1098 ± 69 mg·d−1). Anterior-posterior spine (L2-L4) and lateral spine (LS) BMD (g·cm−2) were significantly lower (P < 0.050) for CYC (L2-L4 = 1.165 ± 0.023 g·cm−2; LS = 0.781 ± 0.025 g·cm−2) than for CON (L2-L4 = 1.246 ± 0.028 g·cm−2; LS = 0.911 ± 0.027 g·cm−2). Based on t-scores (SD from the young adult reference population mean), 9% of CYC and 3% of CON were classified as osteoporotic, whereas 25% and 10% of CYC and CON, respectively, were osteopenic. Conclusions: Our findings indicated that male cyclists had lower spine BMD than controls, which was not associated with group differences in testosterone. Future studies are needed to elucidate the underlying mechanisms for low bone mass in cyclists....